Form for hollow concrete structures



Nov. 29, 1966 J. P. DORRIS FORM FOR HOLLOW CONCRETE STRUCTURES 3 Sheets-Sheet 1 Filed Jan. 2, 1965 b m g 5 w w a I 5 T Ii mm 1. 0 1 3 0 rfii w j m M m 8 a n U 6 1/ 8 Z 9 0 M8 2 a a Z I l m M T 0 N W E0 A V m L 0 J Y B M ml. 29, 1966 J. P. DORRIS 3288,4425

FORM FOR HOLLOW CONCRETE STRUCTURES S Sheets-Sheet 1 Filed Jan. 2, 1965 INVENTOR.

Nov. 29, 1966 J. P. DORRiS 3, 88,425

FORM FOR HOLLOW CONCRETE STRUCTURES Filed Jan. 2, 1963 I5 Sheets-$heet 3 IN VEN TOR.

United States Patent Ofihce 3,288,425 FORM EUR HOLLGW CQNCRETE STRUCTURES John P. Dorris, 5301 River Ave, Newport Beach, Calif. Filed Jan. 2, 1963, Ser. No. 249,015 8 Claims. (Cl. 249-153) This invention relates generally to forms for use in making hollow structures from concrete and the like, and more particularly to an improved design for such forms embodying a minimum number of components.

In constructing hollow structures, such as underground vaults, tanks, pontoon floats, and the like, from concrete and similar materials, it is the usual practice to pour the mixture of material into a form where it is allowed to set and harden. These forms, which usually consist of an inner member and an encircling outer member, are so constructed, and are of such a configuration, as to mold the cast material into the desired shape. Where structures are to be manufactured in great numbers, it is highly desirable that the forms utilized be constructed for ready assembly and disassembly, and that they be reusable indefinitely.

The improved form or mold of the present invention includes a pallet, or fiat frame, upon which is mounted an outer, generally rectangular shell open at both ends, i.e., top and bottom. Disposed within the outer shell in spaced relationship thereto is at least one inner, generally rectangular, inverted, cup-like shell, which is also secured to the pallet. The internal surfaces of the outer shell and the external surfaces of the inner shell are so shaped and finished that they will not become embedded in the articles being cast, and both shells are constructed for easy assembly and disassembly. The inner shell, in particular, is so designed that it can be partially collapsed and readily removed from the finished casting.

Similar forms presently in use possess many disadvantages, one of which is that it is often diflicult to assemble the inner and outer shell members in the desired relation. The design of the present invention overcomes this difiiculty through the use of a specially constructed pallet, which is so designed as to automatically insure that the shell members are assembled thereon in the correct relationship. Another problem in many prior form constructions is the multiplicity of elements employed, which necessarily results in the expending of considerable time in assembly and disassembly. This disadvantage is overcome in the present invention by reducing the number of parts to a minimum through the use of integral shells and bracing elements, and by using a minimum number of fastener elements.

Perhaps the most serious drawback to many present forms is the difliculty often encountered in removing the forms from the finished casting. The removal of an inner, cup-like shell from a cavity in a finished casting is often especially difficult. The inner shell of the present invention is constructed with a very smooth finish on all surfaces which engage the concrete, there being no breaks or corners into which the mix can flow to subsequently set and harden and interlock therewith. Further, the side walls of the inner shell have a slight inward taper to facilitate its removal, and all corners of the inner and outer shells are chamfered, or rounded, to eliminate any possible place where the concrete might become keyed thereto. In addition to these features, the inner shell is constructed so that it can be partially collapsed manually to facilitate removal thereof from within the finished castmg.

The mold of the present invention can be used to cast pontoons for floats and the like and includes a generally rectangular outer shell and one or more generally rectangular inner shells, both the inner and outer shells being attached by a flange and bolt arrangement to a rec- 3,288,425 Patented Nov. 29, 1966 tangular base or pallet. The outer shell is made of two parts detachably secured together by suitable fasteners, and externally braced to retain its configuration under substantial internally applied forces.

The inner shells are unitary and each has an integral internal brace and is further provided internally with turn-buckles for partially collapsing the side walls of the shell to facilitate removal from a cast object. The edges and corners of the internal and external shells which engage the cast object are all chamfered or rounded, and the sidewalls of the internal shell are tapered inwardly slightly to further facilitate removal thereof from said object.

The inner shell is internally braced to insure that it Will maintain a smooth external surface of the proper configuration. When the cast material has hardened, the integral brace structure, which is mounted within the shell to facilitate handling thereof, is removed. The inner shell is also provided with turnbuckle-equipped tie rods secured to and interconnecting the opposed sidewalls of the shell. The tie rods are so arranged that tightening of the turnbuckles, after removal of the integral brace structure, will bow the sidewalls inwardly and also slightly move inwardly the corners of the shell, thus partially collapsing the shell and freeing it from engagement with the hardened concrete. The removal of the inner shell is thus made simple and requires a minimum of time and effort.

The handling of prior forms while the cast products are still disposed therein also often has presented a problem in effecting inversion to remove the cast products. In the present invention, the mold form as a whole is so constructed that it can be handled with relative ease, and can be moved or inverted without damage. To facilitate inversion, the outer shell is provided with a pair of trunnions, which are so positioned relative to the center of gravity of the combined form components and casting that the entire form is automatically rotated to an inverted position when lifted a sufficient distance above the ground, or other supporting surface. Thus, the combined form and casting can be positioned for easiest removal of the latter.

It is the principal object of this invention to provide an improved form for use in casting hollow objects from concrete and the like, and which form is so constructed that its components can be readily and rapidly assembled and disassembled, and repeatedly utilized.

Another object is to provide cooperating mold shells for use in casting hollow objects from concrete and the like, so constructed that they can be easily and quickly removed from a hardened cast object.

A further object is to provide an inner shell, constructed so that it can be partially collapsed for easy removal from an object in which it has been cast.

It is also an object to provide a form for use in casting objects from concrete and the like, wherein the surfaces of the shells in engagement with said object are so constructed as to prevent interlocking therewith.

A still further object is to provide a mold comprising a minimum number of components, so constructed that the relative positions thereof are predetermined in the ultimate assembly.

Yet another object is to provide a mold component having trunnions thereon, so arranged and constructed that it can be readily moved or inverted while containing a cast object.

A more specific object is to provide a mold structure for casting pontoons that can be used in constructing wharves, floats, etc.

Still further objects of this invention are to provide a form which may be economically constructed, and which will permit rapid and economical manufacture of hollow cast objects.

Other objects and many of the attendant advantages of this invention will be readily appreciated as the same become better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein:

FIG. 1 is a plan view of a form or mold structure embodying the invention wherein a portion of the bottom of one of the inner shells is broken away to show its internal bracing structure;

FIG. 2 is a front elevation of the complete form;

FIG. 3 is a right end elevation, particularly showing the trunnion attached to the outer shell;

FIG. 4 is a sectional view, taken on line 4-4 of FIG. 1, showing the details of construction on the joint between the halves of the outer shell;

FIG. 5 is a longitudinal cross-sectional view, taken generally on the line 5-5 of FIG. 1, but with concrete contained in the mold and showing in particular the construction of the inner shells and the manner in which they and the outer shell are secured to the pallet;

FIG. 6 is a transverse cross-sectional view, taken on the line 66 of FIG. 5;

FIG. 7 is a fragmentary sectional view, taken on line 7--7 of FIG. 6, showing the manner in which one leg of the integral brace is fastened to the inner shell;

FIG. 8 is an exploded perspective view of the major components of the mold, a portion of one of the inner shells being broken away to show the interior thereof; and

FIG. 9 is a view of the interior of one of the inner shells, showing the manner in which the turnbuckles can be operated to alternately brace and partially collapse the walls thereof, the inwardly bowed positions of said walls being indicated by broken lines.

Referring now to the drawings and to FIGS. 1 to 3 and 8 in particular, a pallet or supporting frame is indicated at 2, and includes three I-shaped, parallel transverse support beams 4, 6 and 8, and a pair of longitudinal H-shaped side support beams 10 and 12, the latter being disposed upon and welded to the transverse beams near the opposite ends thereof. Each H-shaped beam 10 and 12 has an inverted channel-shaped, side member 14 or 16 dsiposed centrally thereover, said channel members being welded to and having a that of their associated beams. Inverted channel-shaped end-intermediate-end cross members 18, 20 and 22, respectively, welded at their opposite ends of the side channels 14 and 16 are diagonally cut as indicated at in FIG. 8. The interconnected channel, I-beam and H-beam members thus form a rigid, integral frame.

Disposed upon the pallet 2 is an outer shell 24, comprising two sections 26 and 28, which are secured together by bolts 30. The section 26 includes a contiuous metal sheet 32, bent into a U-shape, and the section 28 includes a similar U-shaped sheet 34. The sheet 32 has sides 32a and an end 32b, connected by curved corner portions 88, and the sheet 34 has sides 34a and an end 34b connected by curved corner portions 90. Attached to the lower extrenal edges of the sides 32a and 34a of the sheets 32 and 34, respectively, by welding are L-shaped angle members 36 and 38, respectively, the projecting portions of which form flanges 40 and 42 which rest upon the channel members 14 and 16. The flanges 40 and 42 have a width less than half that of the channel members 14 and 16, and the sheets 32 and 34 are so dimensioned in width relative to the pallet 2 that the outside edges of said flanges are flush with the outside edges of said pallet. Similar angle members 44 and 46 are welded to the bottom edges of the ends 32b and 34b of sheets 32 and 34, respectively, and define flanges 48 and 50 which rest upon channel members 18 and 22, respectively. The side flanges 40 and 42 and the side channel member 14 and 16 each have spaced, aligned bores therein through which bolts 52 and 54, respectively, pass, said bolts having nuts threaded thereon and functioning to secure the sections width about three times extend above the beams 4, 6 and 8, and are 4- 26 and 28 to the pallet. Similarly, the flanges 48 and 50 and the cross channels 18 and 22 have confronting bores therein within which are received, respectively, bolts 56 and 58, nuts being threaded thereon for further securing the sections to the pallet.

Extending horizontally on the sides 32a of section 26 and welded thereto are inverted channel-shaped upper and lower braces 60 and 62, the section 28 having similar upper and lower braces 64 and 66 thereon. The braces 60 and 64 are flush with the upper edge of the sheets 32 and 34, respectively, and the braces 62 and 66 are located about midway of the height of said sheets. Attached by welding in overlapped relation to the vertical edges of U-shaped sheet 32 are angle members 68, each having an outwardly projecting flange 70 thereon. The ends of channel members 60 and 62 are notched to fit over the other flange 71 of said members.

The section 28 has similar angle members 72 attached thereto at a distance back from the vertical edges of sheet 34 and provide outwardly extending flanges 74. The distance that the front edges of sheet 34 extend beyond flanges 74 is equal to the distance that angle members 68 overlap the confronting edges of sheet 32, whereby, as shown in FIG. 4, the joint between the two sections 26 and 28 is smooth, sealed, and firmly backed on the exterior. The flanges 70 and 74 have confronting bores therein for receiving the bolts 30, which have nuts threaded thereon for detachably securing together the sections 26 and 28.

The ends 32b and 34b of sections 26 and 28, respectively, have vertical channel-shaped braces 76 and 78, respectively, welded thereto, the upright flanges of angle members 44 and 46 being notched to receive the lower ends of said braces. Disposed on opposite sides of the brace 76 are horizontally extending, upper and lower channel members 80 and 82, which are welded to sheet 32. Similar upper and lower channel members 84 and 86 are welded to sheet 34. Thus, it is seen that the outer shell 24 comprising the sections 26 and 28 is rigidly braced externally and will hold its shape even under severe loading from wet concrete contained therein. The smooth, uninterrupted internal surface formed by the sheets 32 and 34 offers no crevices into which wet concrete might flow to set and harden, and the generously rounded corners 88 and 90, respectively, facilitate easy removal of the shell from the set cast product.

To further insure that the sidewalls of the shell 24 do not spread at the top, a T-shaped brace 92 extends thereacross at a point to the right of the flanges 70 and 74, and is secured in position by bolts 94, which pass through aligned openings in the ends of the brace 92 and in the channel-shaped braces 64, nuts being threaded on said bolts to fasten them in position.

Disposed within the outer shell 24 are two identical inverted, cup-like, inner shells 96. While two shells are shown, it is to be understood that the number employed can be varied and is dependent upon the configuration desired for the finished cast article. The inner shells 96, as is best seen in FIGS. 1 and 8, each include fiat side plates 98, flat end plates 100, and a flat bottom or closure plate 102. Each of the side plates 98 has an inturned flange 104 along its top edge, and similar inturned flanges 106 along its side edges. The end plates have inturned flanges 108 along their top edges. The flange on all the plates are inclined inwardly on about a 45 degree angle. The edges of the flanges 106 mate with the edges of the end walls 100, and the edges of the flanges 104 and 108 mate with the edges of the bottom wall 102. These mating edges are secured together by internal seam welds, after which the external surface of the shell is finished to remove any welding burrs or rough edges. Triangular, flat corner pieces 110, FIG. 8, are welded in place at each upper corner to fill the gaps between the plates and flanges and to render the shell watertight, Here again, all welds are smoothed exteriorly. It is thus seen that all external edges of the shells 96, as well as the upper corners, are chamfered and smoothed off, whereby to facilitate removal thereof from a cast article. Further, as is best seen in FIGS. 5 and 6, the upright walls of the inner shells 96 are constructed to taper slightly or converge inwardly toward the wall 162, the taper being exaggerated in the drawing for purposes of clarity. This tapered configuration contributes further to easing the removal of the shells from the cast product.

Each shell 96 is braced internally to insure that it will maintain its shape and not yield under loading from wet concrete. The closure plates 2 have diagonally disposed rectangular bars 112 and 114, FIG. 9, welded to their interior surfaces, it being understood that bars of other configurations might also be employed. The side plates 98 and end plates 100 each have a plurality of vertical, parallel, T-shaped reinforcing braces 116 welded thereto and extending interiorly for the full height of the plates to strengthen said plates against undesirable internal bowing. Such bowing, if allowed, would permit the wet concrete to form concave depressions in said plates; such depressions, upon hardening of the concrete, would cause interlocking of the shell and the cast article, and make removal of the shell dilficult, if not impossible.

The braces 116, as is best seen in FIGS. 1, 5 and 6, are disposed opposite one another on confronting side walls, and are connected by an integral assembly of transverse and longitudinally extending brace bars 118 and 120. The bars 120 lie upon and are welded to the bars 118 at points of intersection therebetween and form a unitary, latticelike internal brace generally identified by the numeral 122. The manner in which the brace bars are connected to the T-shaped braces is illustrated in FIG. 7, wherein is shown the end of a transverse bar 118. A pair of plates 124 is welded to the bar 118, and form a bifurcated end for receiving the leg of the T-shaped brace 116. A bolt 126 passes through the plates 124 and 'brace 116, and is secured in position by a nut threaded thereon. Each of the ends of the bars 118 and 120 is secured to one of the braces 116 in the same manner. The unitary brace 122 lies in a plane at about one-third the height of the inner shell 96 and functions to maintain the proper spacing between the opposite walls of said shell during pouring of the wet concrete.

Disposed vertically and medially of the side end plates, respectively, of each shell 96 are outwardly facing channel-shaped members 128 and 130, respectively. These extend for almost the full height of the plates and are welded in position. Extending between each pair of opposed channel members 128 is an adjustable brace 132 comprising two oppositely threaded rods of unequal length connected by a turnbuckle 134, the opposite ends of said brace having short transverse pieces of rod 136 connected thereto which are welded to the back of said channel members. Similar brace rods 13 8, having a turnbuckle 140, are welded to each pair of channel members 130 and extend therebetween. The braces 132 and 138 are disposed in a horizontal plane located about midway between the wall 102 and the brace structure 122 and serve two functions. The first is to assist the integral brace 122 in rendering the shell 96 rigid during pouring of concrete into the form. To this end, the turnbuckles 134 and 140 are turned to extend their respective brace rods to where they provide substantial resistance against inward bending of the plates comprising the upright walls of the shell.

The second function of the brace rods 132 and 138 is to assist in removal of the inner shells 96 from a cast product. Thus, when it is desired to so remove a shell 96, the bolt 126 are first removed and the integral brace 122 is taken out of said shell. The turnbuckles 134 and 140 are then tightened, which tends to partially collapse the upright walls of the shell. The manner in which the shell walls are moved or bowed inwardly is shown in broken lines in FIG. 9, wherein not only the side and end plates 9-8 and 100, but also the corners, tend to move inwardly, the movement of the latter, of course, being quite limited. This partial collapsing of the inner shell 96, coupled with the chamfered edges at all points of juncture of the shell walls, the slight taper of the upright walls, and the smooth, unbroken external surface thereof, makes its removal quite easy, particularly if the external surfaces were coated lightly with a suitable lubricant before the mix wa poured.

The material used for the sheets 32 and 34 is normally thin guage sheet steel, a suitable guage being 12. Similarly, the plates forming the shells 96 may be of sheet steel, 10 guage being suitable for most applications, which provides for the above bowing. Typically, the inner shells 96 may be about 28 inches in depth, in which instance the four plates forming the walls of the shell should taper inwardly about one-half inch. The outer shell, although it is not so illustrated in the drawing, is also preferably furnished with a slight taper.

The inward bowing of the side and end plates of the shells 96 is materially aided by the use of the channel members 128 and 130, which tend to cause the collapsing forces to be applied over the full height of the shell. Also, the vertical T-shaped braces 116, by preventing horizontally-extending depressions from forming in the plates under pressures from the wet concrete, further facilitate the inward collapsing movement occurring upon tightening of the turnbuckles 134 and 140.

The structure whereby the outer shell 24 is fastened to the pallet 2 has already been described, and includes bolts 52, 54, 56 and 58. The structure for securing the inner shells 96 in position on the pallet 2 includes a plurality of spaced, upwardly-projecting lugs 142, FIGS. 5, 6 and 8, welded to the inner edge of channel members 14, 16, 18 and 22, and to both edges of channel member 20. The lugs 142 each have a tapped opening therein for receiving a bolt or set screw 144 of any desired type. The side plate 98 and the end plates of the shells 96 have welded to their lower edges inwardly-projecting flanges 146 and 148, respectively, positioned to rest on the pallet frame 2 and to cooperate with the lugs 142 and set screws 144 for securing the shells 96 to the pallet. The thickness of the flanges 146 and 148 is preferably just slightly less than the distance between the bottom of the transversely disposed set screws 144 and the top surface of the channel member upon which the flanges rest, whereby the shells 96 will be tightly secured in position.

Because the inner shells 96 must be precisely spaced from the outer shell 24 to produce accurately cast objects, means for automatically insuring the desired spacing is provided. Referring to FIGS. 5 and 6, the lower edges of the sheet 32 have welded thereto inwardly-projecting spacer flanges 150, the width of which is equal to the desired spacing between the left inner shell 96 and outer shell section 26. Similarly, the sheet 34 of outer shell section 28 has inwardly-projecting spacer flanges 152 welded to the lower edges thereof. The intermediate channel member 20 has a spacer strip 154 welded thereto, its width being equal to the desired spacing between the two inner shells 96.

The manner in which the improved .mold of the present invention is utilized in the casting of hollow objects is as follows:

The shell sections 26 and 28 are first secured together by the bolts 30, and the assembled outer shell 24 is placed on the pallet 2 and is fastened in position by the bolts 52, 54, 56 and 58. The integral braces 122 are placed within the inner shells 96 and are fastened in position by bolts 126, the turnbuckles 134 and being manipulated to extend or contract brace rods 132 and 138 to such extent as is necessary to adjust the walls 98 and 100 for mounting of the brace 122 therebetween. The inner shells 96 are then placed upon the pallet 2 in inverted position, where they are properly positioned by the spacer flanges 150 and 152, and spacer strip 154, after which the set screws 144 are inserted and tightened. Brace 92 for the outer shell 24 is installed, and the inner surfaces of the outer shell and the outer surfaces of the inner shells may then be lightly coated with a suitable lubricant, after which the form or mold is ready for use.

When the form is to be used, the pallet 2 normally rests upon the ground, or some other supporting surface, after which wet concrete 156, or the like material, is poured thereinto and leveled off. The concrete 156 flows into the space defined by the confronting walls of the inner and outer shells, where it is allowed to set and harden. After hardening of the casting, the form is removed.

The brace 92 may be first removed, after which it normally is desirable to invert the combined cast object and its confining form. To facilitate the latter, the end walls 321) of the outer shell sections 26 and 28, respectively, are provided with trunnions 158 and 160, respectively. To this end, the channel member 76 on shell section 26 has a short, inwardly-facing channel section 162 welded thereto, to which the trunnion 158 is secured. Similarly, the trunnion 160 is attached to the channel member 78 of the outer shell section 28 by a channel member 164 welded thereto. The trunnions 158 and 160 are so positioned relative to the height of the form that their axis is substantially in the plane of the center of gravity of the combined cast object and form, whereby upon lifting of the combined structure by a suitable crane attached to the trunnions, rotation about a line passing through said trunnions will be easily eifected. By positioning the trunnions slightly below such center of gravity, the form and casting will automatically be inverted upon lifting of the form.

After the combined cast object and form are inverted, the pallet 2 is removed. The sections 26 and 28 are then disconnected and separated by removing the bolts 30, thus leaving only the inner shells 96 in position in the casting. The integral braces 122 are next disassembled from the latter upon removal of the bolts 126, after which the turnbuckles 134 and 140 are manipulated in the manner described hereinbefore to partially collapse the walls 98 and 100 of the inner shells 96. The shells 96 are then removed, and the form is reassembled for reuse.

In certain applications, it may be found that the brace rods 132 and 138 will provide sufficient rigidity for the inner shell, in which case the integral brace 122 can be dispensed with. The vertical, T-shaped braces 116 should still be retained, however, for the hereinabove explained reason that they tend to prevent deflection of the upright walls of the inner shell 96, which might cause said shell to become keyed to the object being ca t.

The importance of the chamfered corners and edge on the inner shell, the rounded corners on the outer shell, and a smooth, unbroken finish for the confronting surfaces of both shells is again emphasized, as these insure that the form will not become interlocked with the object being cast therein but, rather, will be easily removable.

The concrete casting resulting from the use of the particular form sections disclosed herein has two separate chambers formed by the two inner sections 96. Such casting may be used as a pontoon in constructing floats, wharves, and the like.

From the foregoing, it is readily seen that a form has been provided which is relatively easy to use, and whose principles of design are particularly adapted for volume production of a large variety of hollow objects.

Obviously, many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described.

I claim:

1. A form for use in making hollow cast objects, comprising: a pallet; an outer generally rectangular shell open at its upper and lower ends, and detachably secured at its lower end to an upper surface of said pallet; at least one generally rectangular integral inner shell having flexible side and end walls disposed within said outer shell in spaced relation thereto and having inwardly extending, spaced apart flanges at the lower end of said side and end walls detachably secured to said upper surface of said pallet, the external, forming surfaces of said inner shell being unbroken; and means attached to and contained within said integral inner shell operable for alternately bracing said integral inner shell when mounted upon said pallet, and for partially collapsing said side and end Walls thereof when said integral shell is detached from said pallet, said spaced apart flanges permitting said collapsing of said side and end Walls.

2. A form as recited in claim 1, including means sccured to the upper surface of said pallet and to the lower edges of said outer shell for positioning and maintaining said integral inner shell in predetermined spaced relation to said outer shell.

3. A form as recited in claim 1, including reinforcing means attached to the exterior of said outer shell; and lattice-like unitary brace means within said integral inner shell detachably connected to and extending between the opposite side and end walls thereof.

4. A form for use in making lhOllOW cast objects, comprising: a pallet; a hollow, generally rectangular outer shell open at both its top and bottom and detachably secured at its bottom edge to said pallet, said outer shell comprising two generally U-shaped sections each having an end wall and side walls extending therefrom at substantially right angles, said sections being detachably secured together; at least one inner shell substantially smaller than and disposed within said outer shell; spacer means on said pallet for engaging and positioning said inner shell in predetermined spaced relation to said outer shell in spaced relation thereto; means detachably securing the bottom edge of said inner shell to said pallet, said inner shell being integral and including a pair of side walls and a pair of end walls constructed of flexible sheet material and interconnected at their adjoining edges to form -a rectangle, the external, forming surfaces of said inner shell walls being unbroken; inwardly projecting flanges at the bottom edges of said outer shell; and means attached to the intermediate portion of each of said inner shell side and end walls, and extending between said side walls and between said end walls of said integral inner shell operable for alternately bracing said integral inner shell when mounted upon said pallet and partially collapsing all of said side and end walls, when said integral inner shell is detached from said pallet, by applying force to the intermediate portion of each of said side and end walls to move inwardly the bottom edges and said intermediate portions of .all said inner shell walls, whereby the intermediate portion of each said side and end wall is flexed inwardly to a greater extent than the remaining portions of said side and end walls on either side of said intermediate portions.

5. A form as recited in claim 4, wherein the means for securing the bottom edge of the inner shell to the pallet includes inwardly projecting flanges at the bottom edges of said shell, a plurality of spaced lugs projecting upwardly from said pallet and positioned adjacent said flanges when said inner shell is in contact with said pallet, and set screws receivable within threaded bores in said lugs and engaging said flanges.

6. In a form for use in the making of hollow cast objects, an integral shell about which moldable material may be poured for forming said cast object, said shell comprising oppositely disposed, interconnected side and end walls each having a bottom edge and being made of flexible sheet material, the bottom edge of each wall having inwardly extending spaced apart flanges thereon for connecting said shell to a pallet, and the forming surface defined by said walls being unbroken; and adj ustable means within said shell attached to and extending between the intermediate portion of each of said side and end walls, and operable for alternately bracing said Walls during a casting operation and partially collapsing said shell to remove it from a cast object, by applying force to the central portion of each of said side and end walls to move inwardly the bottom edges of said central portions of all of said Walls, said means including at least one brace rod attached to and interconnecting said intermediate portions of said opposite side and end Walls, respectively, said brace rod including a pair of rod sections connected by a turnbuckle.

7. In a form for use in making hollow cast objects, an integral shell about which moldable material may be poured for forming said cast object, said shell including a pair Olf upright confronting side walls and a pair of upright confronting end walls connected at their adjoining edges to generally form a rectangle, said walls each having a bottom edge and being constructed of flexible sheet material, the bottom edge of each wall having inwardly extending, spaced apart flanges thereon for connecting said shell to a pallet, and the (forming surfaces of said shell being unbroken; a vertically disposed brace member secured to the inner surface of each ort said side and end walls centrally thereof and intermediate a pair of said flanges; and longitudinally adjustable means attached to and extending between the brace members on said side Walls and between the brace members on said end walls operable for alternately bracing said walls during a casting operation, and partially collapsing said walls to remove said shell from a cast object, by applying [force to the vertical brace member secured to the central portion of each of said side and end walls to move inwardly the bottom edges and said central portions of all of said Walls, said spaced apart flanges permitting said bottom edges to bow inwardly.

8. A form as recited in claim 7, including vertically disposed reinforcing members on the inner surface of each well on either side of the centrally disposed brace member thereon, and a unitary cross brace structure detachably connected to the reinforcing members on all of the walls and extending across the shell between the confronting Walls.

References Cited by the Examiner UNITED STATES PATENTS 941,139 11/1909 Galasse 25130 969,299 9/ 1910 Rathbun 25130 995,354 6/1911 Kipp et al. 1,137,932 5/1915 Vi-ckers 25130 1,292,093 1/ 1919 Schmuck 25130 1,568,957 1/1926 Camp 25130 1,610,396 12/ 1926 Tinker 25130 1,665,027 4/ 1928 Haley. 1,856,589 5/1932 Peterson et al 25-131 1,913,178 6/1933 Walker 25130 2,182,808 12/1939 Holtz 25130 2,307,678 1/ 1943 Hayes 25130 2,511,584 6/1950 Hill 25131 2,578,310 12/1951 Lager 25130 2,616,146 11/ 1952 Haase. 2,731,698 1/'1956 Tunsen. 2,807,071 9/ 1957 Francis et al. 2,865,078 12/ 1958 Hasselblad. 2,894,311 7/1959 Sinclair. 3,035,324 5/ 196 2 Milne.

J. SPENCER OVERHOLSER, Primary Examiner.

MICHAEL V. BRINDISI, WILLIAM J. STEPHENSON,

Examiners.

G. A. KAP, I. H. FLINT, Assistant Examiners. 

1. A FORM FOR USE IN MAKING HOLLOW CAST OBJECTS, COMPRISING: A PALLET; AN OUTER GENERALLY RECTANGULAR SHELL OPEN AT ITS UPPER AND LOWER ENDS, AND DETACHABLY SECURED AT ITS LOWER END TO AN UPPER SURFACE OF SAID PALLET; AT LEAST ONE GENERALLY RECTANGULAR INTEGRAL INNER SHELL HAVING FLEXIBLE SIDE AND END WALLS DISPOSED WITHIN SAID OUTER SHEEL IN SPACED RELATION THERETO AND HAVING INWARDLY EXTENDING, SPACED APART FLANGES AT THE LOWER END OF SAID SIDE AND END WALLS, DETACHABLY SECURED TO SAID UPPER SURFACE OF SAID PALLET, THE EXTERNAL, FORMING SURFACES OF SAID INNER SHELL BEING UNBROKEN; AND MEANS ATTACHED TO AND CONTAINED WITHIN SAID INTEGRAL INNER SHELL OPERABLE FOR ALTERNATELY BRACING SAID INTEGRAL INNER SHELL WHEN MOUNTED UPON SAID PALLET, AND FOR PARTIALLY COLLAPSING SAID SIDE AND END WALLS THEREOF WHEN SAID INTEGRAL SHELL IS DETACHED FROM SAID PALLET, SAID SPACED APART FLANGES PERMITTING SAID COLLAPSING OF SAID SIDE AND END WALLS. 